<html>
<head>
    <title>Concealed element test</title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }
        ol {
            padding-top: 160px;
        }
        li {
            height: 80px;
            border: 1px solid black;
        }
        .sticky {
            z-index: 9999;
            width: 100%;
            position: fixed;
            height: 160px;
            background: black;
        }
    </style>
</head>
<body>    
    <div class="sticky"></div>
    <ol>
        <li>item 1</li>
        <li>item 2</li>
        <li>item 3</li>
        <li id="concealed">item 4</li>
        <li>item 5</li>
        <li>item 6</li>
        <li>item 7</li>
        <li>item 8</li>
        <li>item 9</li>
        <li id="last">item 10</li>
    </ol>

    <script type="text/javascript">
        window.clickResult = '🙈';

        el = document.querySelector('#concealed');
        el.addEventListener('click', function (ev) {
            ev.preventDefault();
            window.clickResult = "🐵";
        })
    </script>
</body>
</html>